Valve seat grinding tool



Oct. 6, 1936. H. c. PRESTON VALVE SEAT GRINDING TOOL Filed May 5, 1935 o0 v y o W O o w l a JF d 0 3 j 7 @u .ou I @if WM Cid, k M Z1 j I M 00 7 Z Patented Oct. 6, 1936 UNITED STATES VALVE SEAT GRINDING TOOL lilenryr C. Preston, Baltimore County, Md., as-

signor to The Black & Decker Manufacturing Company, a oorporati on of Maryland Application May 5, 1933, Serial No. 669,533 19 Claims. (Cl. 51-241) Due to the use of valve seats in the form of hard steel inserts in internal combustion motors in place of the old type of seat which was formed directly in the case iron engine block, the method .of surfacing and resurfacing' the seating surface by roaming which was in general vuse has been abandoned and replaced by grinding. This operation is performed by means of a cutting stone and must not be confused with the old lapping operation in which surfacing is accomplished by oscillating the valve in the seat, the contacting surfaces being coated with abrasive paste. This method is relatively slow and inaccurate. Various machines have been devised for lapping and some forgrinding valve seats, but the machines which have so far been produced and offered for sale for these purposes are relatively complicated, cumbersome, expensive and inefficient.

In the grinding operation in connection with which the apparatus of the invention has been developed, it has been found that the best results can be obtained by continuous rotation of the stone at high speeds, the cutting being performed rapidly and in order to prevent loading up of the cutting stone with a consequently poor surfacing job, the stone is lifted from the seat at intervals to allow the particles of stone and steel to be thrown out whereby the seating surface which is being formed and the stone are cleared of this accumulation. l j

The object of the present invention is to produce a simple, efficient and relatively cheap machine which operates at high speed, cuts rapidly and gives the desired lifting of the cutting stone 35 from the seating surface. This operation is performed automatically at short intervals which are so timed as to keep the cutting uniform and true leaving the operator free to support and direct the machine and control its operation, pro- 40 ducing the highest quality of work with the least expenditure of time and effort.

In accordance with the preferred form of invention as herein disclosed, the stone is driven directly from the armature shaft of a universal 45 motor at a speed of from 10,000 to 12,000 R. P. M., the tool spindle with the tool connected thereto being vibrated in the direction of its length as it is rotated, the timing'of the vibrations being in the preferred form automatically varied in its 55 surface, being formed. While'the speeds stated relation to the rotation of the stone. The lifting are the preferred speeds, other grinding speeds may be employed.

The cutting 'stone may to the best advantage be mounted on a sleeve which is connected to the tool shaft by'a universal joint. When this de- 5 vice is employed, the tool is guided in its operationr by means of a pilot which is seated in the valve stem guides and extends upwardly through the stone and through the sleeve upon which it is mounted, the stone and sleeve being free to 10 slide up and down and rotate on the pilot.

In the accompanying drawing I have illustrated a vibrating valve seat grinder embodying the features of my invention in the preferred form.

Figure l is a fragmentary vertical central 15 cross section of the machine, certain parts being shown in elevation, the valve seat and storie being included.

Figure 2 is an elevation of the tool with 'the stone and shaft detached. 20

Figure 3 is an elevation of the tapered rings and balls. f

Referring ,to the drawing by numerals,.each of which is used to indicate the same or similar parts in the different figures., the construction 25 shown comprises a portable power driven rotary tool l, which is preferably provided with a hand grip 2 convenient to which is a switch or other device 3 for controlling the operation of the tool. This tool inthe preferred form of the invention 30 is electrically driven having a motor 4 mounted -in a suitable housing or casing 5 to which the grip 2 is secured. 'I'he motor 4 is to the best advantage of the universal high speed type,'having a speed around 10,000 to 12,000 R. P. M. though these particular speeds and this particular type of motor are not regarded as essential to the operation of the invention, and other methods of effecting rotary motion of the cutting stone being available in this connection.

The armature lshaft 6 of the motor 4 is supported and guided in suitable bearings 'l mounted in an extension 8 of the frame or housing 5 and the motor as shown is cooled by means of a fan 9 which` may be utilized in any suitable manner.

I n the form of the invention shown the armature or motor shaft 6 is provided at its end Il remote from themotor with a cylindrical or other suitable socket I2-of the telescoping type, at the bottom of which is a slot i4. The to'olshaft I5 50 is shown as mounted in suitable guide bearings I6 "at the lower end of the frame-extension 8 and in alignment with ythe motor or armaturer shaft 6 and this shaft I5 is provided at its upper end with a telescoping member I1 adapted to have a sliding 55 engagement with the socket I2, the tool shaft I5 being connected to the motor shaft 6 to rotate therewith by means of a tongue I8 which nts in the slot I4 at the bottom of the socket. However, this telescoping connection may be effected in any suitable and convenient manner. Below the telescoping member I1 the tool shaft I5 in the form of the invention shown is suitably threaded and provided with lock-nuts I9 engaging the thread and bearing on a washer 20 which encircles the tool shaft, which shaft is preferably shouldered at this point and enlarged as illustrated. Immediately below the washer 20 are two tapered cam rings 2I and 22, spaced apart by means of balls 24 positioned by means of a ball race or ring 25 or in any suitable manner, or any suitable antifriction means may be employed.

The upper tapered ring 2I bears on the bottom of the washer 20 and the lower ring 22 on the top surface 28 of the casing extension 8 where it surrounds the bearing I6.

The rings 2| and 22 are best illustrated in Figure 3 where they are shown in connection with the balls 24 and ball race 25. 'Ihese rings preferably have a gradual taper from one diametrically opposite side to the other, the difference in thickness at the two diarnetrically opposite sides of each ring at the high and low points being about 1/64" in the form of apparatus illustrated. The taper or inclination of the rings is exaggerated in the drawing for purposes of illustration as the actual inclination, if produced to scale, would hardly be visible. The rings have a gradual cam action as hereinafter described, whereby all possible tendency to hammering or pounding is avoided. A spring' I3 coiled about the lower end of the shaft 6 bears at one end against the bearing 1 and at the other end against the lock nut I9, imparting a downward tendency to shaft I5 and upper tapered cam ring 2l.. 'I'hus cam ring 2I is kept in contact with balls 24 and the latter are held in contact with lower tapered cam ring 22.

'I'he portion of the tool shaft I5 within the bearing I6 is fitted to run in the bearing with a suitable running fit in accordance with the regular practice, and the tool shaft is provided at its lower end with ball 29 of a universal or any suitable or equivalent type of joint, preferably one which is easily engaged and disengaged as hereinafter described.

In the form of the invention shown this ball 29 varies somewhat from the spherical, being of hexagonal cross section so that it has six tapered meridianal surfaces 30, though the details of this construction are not essential. The ball member 29 as shown is connected to the upper portion of the tool shaft I5 by means of a reduced shank or neck 3 I. The other or lower member of the unlversal joint referred to indicated by reference character 33 in the preferred form of the invention shown consists of a hexagonal cup secured to the upper end of the tool shaft or sleeve 34 which carries the cutting stone 35. This grinder sleeve or shaft 34 is shown as provided with circular radially projecting fins or vanes 36 which assist in dispensing and radiating the heat which results from the grinding operation, in this way cooling the shaft, the stone and particularly the valve seat being treated.

In the valve seat grinding or finishing operation, the valve being removed from the seat, a pilot 21 is secured in the valve guide in any suitable or preferred manner. The portion of the pilot at 31 which projects above the valve seat has a running llt inside of thecentral bore 38 of the hollow shaft or sleeve 34 so that the sleeve 34 and stone 35 move freely up and down on the pilot and rotate relatively thereto in the cutting operation, the stone being in this way centered relatively to the valve stem guide.

In the operation of resurfacing or grinding valve seats, the valve having been removed, the pilot is'placed in the valve guide and secured in any suitable manner as aforesaid with its axis in alignment with the axis of the valve guide. The cutting stone 35 being rst attached to the shaft or sleeve 34, the cutting stone and sleeve are passed over the pilot as aforesaid, and the stone is engaged with the surface of the valve seat 39. The ball 29 is then seated in and engaged with the hexagonal socket 33, the power operated rotary tool I being held by the operator in substantial alignment with the pilot, and the control switch 3 is pressed, energizing the motor whereby the stone is rotated at a suitable speed preferably around 10,000 to 12,000 R. P. M., being held in contact with the seat at cutting pressure by the weight of the tool and any such application of thrust thereto as may seem suitable to the operator, a yielding contact being effected by the spring I3 which also holds the rings 2I and 22 in contact with the balls 24. 'I'he upper cam ring or tapered ring 2I has a tendency to rotate with the tool shaft I5 and the washer 20 which is in contact with the lower surface of locknut I9, and is in the preferred form so fitted as to rotate with the shaft I5 at the speed of the shaft being seated on a shoulder on the spindle I5, and forced downwardly against the shoulder by the nuts I9. 'I'he resulting drive provides for a slip of the ring 24 relatively to the washer or flange 20 so that the ring 24 has a creep or slip friction drive. The lower cam ring 22 on the other hand being supported on the upwardly disposed surface 28 of the casing tends to remain stationary, but is preferably free so that is moves at a very considerably reduced speed more or less irregularly in the direction of rotation of the shaft. This cam is also referred to herein as an abutment or an abutment cam. It has a slip friction retardation.

As the result of the relative motion of the rings 2I and 22 thus effectedy which gives a cam action due to the slight taper of the rings as described, the balls 24 serving the function of an antifriction device or cam follower, the tool shaft I5 receives a very slight vibrating motion in the direction of its axis at a speed which in the form shown is more or less irregular in its correspondence with and preferably differs from the speed of rotation of said shaft. The connection of this shaft to the grinder sleeve 34 due to the friction of the ball 29 in the socket 33 gives a corresponding lifting of the stone from the seat in the nature of a vibration of the stone into and out of contact with the valve seat. While the rings 2I and 22 have been described as having a frictional engagement only, the ring 2I with the shaft I5 and the washer 20, and the ring 22 with the casing surface 28, these rings may within the scope of the invention be secured respectively, the ring 2I to the shaft I5 or washer 20 and the ring 22 to the casing surface 28 so as to give a definite motion of one relatively to the other ln exact correspondence with the speed of the shaft I5. 'I'he arrangement of the rings as described whereby they are more or less free to drift relatively to the shaft and cam, respectively, is, however, found to contribute to the absolute accuracy of the result, and is regarded as the preferred form of the invention. The spring and the gradual motion of the cam rings mosaics prevent vibration of the tool and hammer of the stone on the valve seat. The spring may be located and applied in any suitable manner.

The lifting of the stone from the valve seat surface on which the grinding operation has been performed has the effect of releasing the particles of stone and steel which are separated from the cutting stone and the valve seat, the rotary motion ofthe stone causing these to be thrown outwardly from the seat and stone. In this way the cutting surface and the seat surface are cleared of this materiall overcoming any tendency to accumulation, otherwise the stone will load' up and give a poor surfacing job. The drifting of the cam overcomesthe effect which might result from any irregularity of the shape ofthe stone and renders the cut absolutely true with the valve stem guide.

While the construction shown is particularly adapted for use in the grinding of hard -valve seat inserts. it has also been found that the tool de scribed will work satisfactorily in the grinding of valve seats whichare formedin cast iron engine blocks and do' better and quicker work than can be accomplished by reaming and much better and quicker and more accurate work than can be performed by lapping. 'j-

The fact will be understood and appreciated that the friction of the stone on the seat generates a considerable amount of heat. This is thrown off and a satisfactory temperature of the seat is maintained whereby burning is avoided by means of the vanes 38 projecting from the-cutter sleeve 34 as already described.

In the preferred form the invention is adapted for use in connection with a portable power driven electric tool ofthe high speed rotary type. though it is capableof-more general application.

I have thus described specifically and in detail a valve seat grinding tool embodying the features of the invention in the preferred form, the description being specific and in detail in order that the manner of constructing. applying, operating and using thesame may be clearly understood, however, thespecific terms herein are used descriptively rather than in a limiting-sense, the scope of the invention being defined inthe claims.

What I claim as new and desire to secure by Letters Patent is:

1. The combination in a hand supported power driven rotary tool having a rotor and a yrotor shaft. of a continuously rotating tool shaft operated from the rotor shaft and movable longitudinally, means for vibrating the tool shaft in the direction of its length as it rotates, including means for-varying the relation of said vibrating means to the speed of rotation causing the vibrating action of vsaid shaft to bear-a varying relation to its speed of rotation, a grinder shaft, means for maintaining -said shaft in alignment with the valve-guides ofA an internal combustion motor, a valve seatl grinding -stonemounted on the grinder shaft and means connecting the tool shaft to the grinder shaft to operate said shaft to rotate the stone on the valve seat and lift it from the valve seat and return it thereto at varying intervals whereby the grit and metal dust produced in grinding are released and thrown off.

2. The combination in a hand supported portable power driven rotary tool lhaving a rotating shaft, a continuously rotating tool shaft, a longitudinally extensible driving connection between said shafts, cam means and slip friction means for driving the same to periodically vibrate the tool shaft in the direction of its length. as it rotates and for varying automatically the relation of the frequency of vibration to the speed of rotation, a grinder shaft, means for maintaining the shaft in alignment with the valve guides, a valve seat grinding stone mounted on the grinder shaft and means connecting the tool shaft to the grinder shaft to rotate the stone and lift it from the valve seat at intervals corresponding to the speed of vibration.

3. The combination with a portable power driven rotary tool having a motor, a rotor shaft, a tool shaft having a longitudinally extensible driving connection with said rotor shaft, slightly tapered cam rings encircling the tool shaft, antifrictionmeans between said rings. an vabutment on the tool shaft bearing against one ring and having a frictional engagement therewith, stationary means for supporting the other ring and having a frictional engagement therewith so that both rings rotate irregularly and at different speeds due to the frictional engagement ofthe cams, a grinder shaft, a valve seat grinding stone on the grinder shaft and a universal joint for connecting the tool shaft to the grinder shaft,

the grinder shaft having means for centering the stone relatively to the valve guides.

. 4. The combination in a valve seat grinding tool having a rotor, a rotor shaft, a tool shaft having a longitudinally extensible driving connection with said rotor shaft, cam rings encircling the tool shaft. the adjacent surfaces of the y rings having a slight substantially uniform incline, antifriction meansv between said rings. means on thetool shaft bearing against the one ring, stationary means for supporting the other ring. a-hollow cuttershaft, a valve seat grinding stone on the hollow shaft.. means for connecting the tool shaft to the cutter shaft. anda spring tending to advance the tool shaft holding the cams in engagement with the transmitting means, and a.. pliot within the hollow shaft.

5. The combination in a valve seatgrinding tool of a high speed universal motor, a motor shaft, a tool shaftv having a longitudinally extensible driving connection with the motor shaft.

relatively rotating cam ringsencircling the tool shaft, the opposed surfaces of the cam rings hav-` ing a slight incline vfor transmitting longitudi nal motion to the tool shaft, means on the tool shaft engaging. the upper ring, a stationary sup.- port for the lower ring. a spring applying pressure to the tool shaft in the direction of the work, av grinder shaft, a valve seat grinding stone on the grinder shaft and a driving connection between the tool shaft and the grinder shaft.

6. The combination in a manually supported 4,portable power driven tool, of a highV speed universal motor, a motor shaft, a tool shaft having a. longitudinally extensible driving connection -with the motor shaft. tapered Irelatively rotating cam rings encircling the tool shaft, balls between the cam rings fortransmitting longitudinal mo- -tion to the tool shaft, an abutment on the tool shaft bearing against the upper ring, a stationary support for the lower ring and a spring applying pressure to the tool shaft in the direction of the work, a grinder shaft, a valve seat grinding stone on the grinder shaft and a universal connection between the tool shaft and the grinder shaft, the grinder shaft being hollow and having an internal guiding surface to engage a valve seat pilot.

7. The combination in a portable power driven rotary tool for grinding valve seats, of internal combustion engines and similar valve seats of a high speed universal motor, having an amature shaft, a tool shaft with a guide bearing in which it is mounted to rotate and to slide in the direction of its axis, a telescoping driving connection between the tool shaft and the amature shaft, a plurality of tapered cam rings encircling the tool shaft, the rings being without positive connection to either the rotary or stationary portion of the tool, one having a frictional connection to and with the tool shaft and the other having a similar engagement with a stationary portion of the frame, a ball ring between the cam rings transmitting the thrust from one to the other, a coil spring applying a thrust to the tool shaft and the cam rings in the direction of the work, the rings being thereby rotated relatively to each other at a speed less than the rotation of the tool shaft whereby the tool shaft is vibrated in the direction of its axis, a hollow shaft adapted to receive a valve guide pilot in sliding and rotary engagement therewith, a valve seat cutting stone mounted on the hollow shaft and a universal joint connecting the tool shaft to the hollow shaft, the vibration of the tool shaft serving to lift the stone from the valve seat at irregular intervals.

8. 'I'he combination in a portable power driven rotary tool for grinding valve seats of internal combustion engines and other valve seats, of a high speed universal motor, having an armature shaft, a bearing therefor, a tool spindle with a guide bearing in which it is mounted to rotate and to slide in the direction of its axis, a driving connection between the tool shaft and the armature shaft, a plurality of tapered cam rings encircling the tool shaft, one having a connection to the too-l shaft to be rotated thereby and the other bearing on a stationary portion of the frame, follower means between the cam rings transmitting thrust from one to the other, the latter ring being rotated relatively to the frame by the friction .of the follower at a speed less than the speed of the first mentioned ring giving a cam action whereby the tool shaft is vibrated in the direction of its axis, a grinder shaft, a valve seat cutting stone mounted on the grinder shaft and means connecting the tool shaft to the grinder shaft, the vibration of the tool shaft serving to lift the stone from the valve seat at irregular intervals.

9. In a valve seat grinder, a valve seat grinding stone and a shaft therefor, the shaft having projecting fins to radiate the heat from the stone incident to the grinding operation.

10. 'I'he combination in a valve seat grinding tool of a high speed driving rotor, a rotor shaft, a tool shaft having a longitudinally extensible driving connection with the rotor shaft, tapered relatively rotatable cam rings encircling the tool shaft, a grinder shaft adapted to carry a valve seat grinding stone, a universal connection between the tool shaft and the grinder shaft, means for centering and aligning the grinder shaft with the valve seat, slip friction means for imparting to the cam rings a relative rotation which varies in its relation to the rotation of the stone serving to vibrate the grinder stone in the direction of its axis at intervals which are irregular in their relation to the speed of rotation of the stone, and a spring for taking up the vibration incidental to the operation of the cams.

l1. In a valve seat grinding tool a rotor, means I for connecting a valve seat grinding stone to the rotor to be driven in rotation thereby at grinding speeds, means for vibrating the stone in the direction of its axis and controlling said vibrating means whereby said vibrations are caused to take place in varying relation to the speed ofA rotation of the stone, said vibrations serving to lift the stone from the seat and release the grit and metal dust which tends to accumulate between the stone and the seat.

12. In a valve seat grinding tool a rotor means for connecting a valve seat grinding stone to the rotor to be driven in rotation thereby at a grinding speed, said means providing for motion of the stone in the direction of its axis into and out of contact with the seat and means for vibrating the stone in the direction of its axis and slip friction means for driving said vibrating means and causing the stone to vibrate with a frequency in indefinite and automatically varied relation to its speed of rotation.

13. In a valve seat grinding tool a rotor means for connecting a valve seat grinding stone to the rotor to be driven in rotation thereby at a grinding speed, said means providing for motion of the stone in the direction of its axis into and out of contact with the seat and means for vibrating the stone in the direction of its axis in indefinite and automatically varied relation to its speed of rotation, said means comprising a cam member, and slip-friction means whereby it is engaged with the drive and an abutment cooperating with the cam to give said vibrating effect.

14. In a valve seat grinding tool a rotor means for connecting a valve seat grinding stone to the rotor to be driven in rotation thereby at a grinding speed, said means providing for motion of the stone in the direction of its axis into and out of contact with the seat and means for vibrating the stone in the direction of its axis in indefinite and automatically varied relation to its speed of rotation, said means comprising a cam member and slip friction means whereby it is engaged to the drive and an abutment co-operating with the cam to effect said vibration, and anti-friction means between the cam and the abutment.

15. In a valve seat grinding tool a rotor means for connecting a valve seat grinding stone to the rotor to be driven in rotation thereby at a grinding speed, said means providing for motion of the stone in the direction of its axis into and out of contact with the seat and means for vibrating the stone in the direction of its axis in irregularly timed relation to the speed of rotation of the stone, said means comprising co-operating rotary cam thrust members, with anti-friction means between them and slip friction means -driving one cam member at a reduced speed from the rotor and retarding the other cam member.

16. The combination in a portable power driven rotary tool, of a rotor shaft, a spindle having a driving connection with the shaft and mounted to move in the direction of its axis, means for connecting a valve seat grinding stone to the spindle to be operated thereby, two members comprising a cam and a co-operating cam abutment whereby the spindle is vibrated in the direction of its axis as it rotates, one said member having a slip friction connection with the drive whereby it is moved in a variable and indefinite relation to the rotation of the spindle, accomplishing said vibration in indefinite relation to the rotation of the spindle.

17. The combination in a portable power driven rotary tool having a rotor a longitudinally movable tool shaft driven from said rotor o:

means for vibrating the tool shaft in the direction of its length as it rotates, slip friction means driving said vibrating means from said rotor at a reduced speed as compared to the speed of the rotor, a grinder shaft, a valve seat grinding stone mounted on the grinder shaft, means for maintaining the grinder shaft in alignment with a valve guide and a frictionally engaged universal joint for connecting the grinder shaft to the tool shaft to lift the stone from its seat as it is operated by said tool shaft through said joint.

18. The combination with a portable power driven rotary tool having a longitudinally movable tool shaft and means for rotating said shaft, of means for vibrating .the tool shaft in the direction of its length as it rotates including means for causing the vibrations to take place in irregularly timed relation to the speed of rotation of the tool shaft, a grinder shaft, a valve seat grinding stone mounted on the grinder shaft, means for maintaining the grinder shaft in alignment with a valve guide and a. universal joint for connecting the grinder shaft to the tool shaft to be connected in rotary driving relation and to 5 yield in the direction of the axis oi' the grinder shaft with a frictional resistance to such yielding which resistance causes said lifting of the stone.

19. In a valve seat grinding tool a rotor. means 10 for connecting a valve seat grinding stone to the rotor to be driven in rotation thereby at grinding speeds, means for vibrating the stone in the direction of its axis including means whereby said vibrations are caused to take place in varying, 15

relation to the speed of rotation of the stone, said vibrations serving to lift the stone from its seat and release the grit and metal dust which tends to accumulate between the stone and the seat,

the speed of rotation of the rotor being from 20 10,000 t0 12,000'R. P. M..

HENRY C. PRESTON. 

